Conventionally, in order to perform gas leakage detection during a stable operation of a fuel cell, the operation of the fuel cell is completely stopped for, for example, one day in a certain period of time (e.g., 30 days). That is, by stopping the fuel cell for one day, a period of time in which a total gas use amount of the fuel cell and gas appliances becomes zero is intentionally generated so as to allow for the gas leakage detection. Therefore, an operating ratio and a power generation efficiency of the fuel cell may possibly decrease.
Especially in using a solid oxide fuel cell, a battery cell needs to be cooled down when the cell is stopped. Therefore, it takes time to restart power generation after stopping the fuel cell, possibly further deteriorating the operating ratio of the fuel cell.
For example, PLT 1 set forth below describes a method of using a gas meter having a fixed amount gas flow path for supplying gas to the fuel cell and a variable amount gas flow path for supplying gas to gas appliances. This method detects the presence/absence of the gas leakage by using a sensor provided on a downstream side in the variable amount gas flow path.